The Jets could be missing a key piece of their defense Sunday at Buffalo.

Defensive lineman Muhammad Wilkerson suffered a concussion in Sunday’s loss to the Chargers and did not practice yesterday. His status for the game with the Bills is up in the air.

Wilkerson played every snap of the Chargers game. He suffered the injury late in the game but did not show any symptoms until afterward, a team spokesman said. Wilkerson underwent concussion tests yesterday. The team did not release the results.

“That’s interesting because obviously at the end of the game that was it,” Jets coach Rex Ryan said. “It was kind of news to me that he has a concussion.”

Wilkerson is also listed on the injury report with a knee injury. Ryan was unsure if Wilkerson would be able to play Sunday against the Bills.

* Quarterback Mark Sanchez said he has learned a lot in his fourth season. Things did not go well for Sanchez this year and he watched last week from the bench and will do the same this week.

“It’s been a great learning experience,” Sanchez said. “Great lessons to learn from and just to be ready when I get my next shot.”

Sanchez said he realizes now the trips to the AFC Championship Game in his first two seasons were harder to achieve than it may have seemed at the time.

“It’s the nature of this business,” Sanchez said. “Fortunately or unfortunately, those first two years were not normal. This is the majority of the NFL every year — not making the playoffs. … That’s real and there’s hundreds and hundreds of guys that have gone through this.”

* QB Greg McElroy appeared on the injury report yesterday with an abdominal injury but practiced fully. Both Ryan and McElroy said the injury is not serious and he will play Sunday. … TE Dustin Keller (ankle), WR Braylon Edwards (hamstring, knee), WR Chaz Schilens (knee), LB Bryan Thomas (chest), CB Ellis Lankster (concussion) and CB Aaron Berry (hamstring) did not practice.